The present invention relates to a display device which consumes less electric power, and which has large screen brightness. In particular, the present invention relates to improvement in the display device for displaying a picture image corresponding to an image signal on an optical waveguide plate by controlling leakage light at a predetermined position on the optical waveguide plate by controlling the displacement action of an actuator element in a direction to make contact or separation with respect to the optical waveguide plate in accordance with the attribute of the image signal to be inputted. The present invention also relates to a method for producing the display device.
Those hitherto known as the display device include, for example, cathode ray tubes (CRT) and liquid crystal display devices.
Those known as the cathode ray tube include, for example, ordinary television receivers and monitor units for computers. Although the cathode ray tube has a bright screen, it consumes a large amount of electric power.
Further, the cathode ray tube involves a problem that the depth of the entire display device is large as compared with the size of the screen.
On the other hand, the liquid crystal display device is advantageous in that the entire device can be miniaturized, and the display device consumes a small amount of electric power. However, the liquid crystal display device involves problems that it is inferior in brightness of the screen, and the field angle of the screen is narrow.
In the case of the cathode ray tube and the liquid crystal display device, it is necessary for a color screen to use a number of pixels which is three times a number of pixels used in a black-and-white screen. For this reason, other problems occur in that the device itself is complicated, a great deal of electric power is consumed, and it is inevitable to cause the increase in cost.
In order to solve the problems described above, the present applicant has suggested a novel display device (see, for example, Japanese Laid-Open Patent Publication No. 7-287176). As shown in FIG. 63, this display device includes actuator elements 400 arranged for respective pixels. Each of the actuator elements 400 comprises a main actuator element 408 including a piezoelectric/electrostrictive layer 402 and an upper electrode 404 and a lower electrode 406 formed on upper and lower surfaces of the piezoelectric/electrostrictive layer 402 respectively, and an actuator substrate 414 including a vibrating section 410 and a fixed section 412 disposed under the main actuator element 408. The lower electrode 406 of the main actuator element 408 contacts with the vibrating section 410. The main actuator element 408 is supported by the vibrating section 410.
The actuator substrate 414 is composed of ceramics in which the vibrating section 410 and the fixed section 412 are integrated into one unit. A recess 416 is formed in the actuator substrate 414 so that the vibrating section 410 is thin-walled.
A displacement-transmitting section 420 for obtaining a predetermined size of contact area with respect to an optical waveguide plate 418 is connected to the upper electrode 404 of the main actuator element 408. In the illustrative display device shown in FIG. 63, the displacement-transmitting section 420 is arranged such that it is located closely near to the optical waveguide plate 418 in the OFF selection state or the NO selection state in which the actuator element 400 stands still, while it contacts with the optical waveguide plate 418 in the ON selection state at a distance of not more than the wavelength of the light.
The light 422 is introduced, for example, from a lateral end of the optical waveguide plate 418. In this arrangement, all of the light 422 is totally reflected at the inside of the optical waveguide plate 418 without being transmitted through front and back surfaces thereof by controlling the magnitude of the refractive index of the optical waveguide plate 418. In this state, a voltage signal corresponding to an attribute of an image signal is selectively applied to the actuator element 400 by the aid of the upper electrode 404 and the lower electrode 406 so that the actuator element 400 is allowed to make a variety of displacement actions in conformity with the ON selection, the OFF selection, and the NO selection. Thus, the displacement-transmitting section 420 is controlled for its contact and separation with respect to the optical waveguide plate 418. Accordingly, the scattered light (leakage light) 424 is controlled at a predetermined portion of the optical waveguide plate 418, and a picture image corresponding to the image signal is displayed on the optical waveguide plate 418.
When a color picture is displayed by using the display device, the following operation is performed. That is, for example, light sources for three primary colors are switched to control the light emission time for three primary colors while synchronizing the contact time between the optical waveguide plate and the displacement-transmitting plate with the period of color development. Alternatively, the contact time between the optical waveguide plate and the displacement-transmitting plate is controlled, while synchronizing the light emission time for three primary colors with the color development period.
Therefore, the illustrative display device suggested by the present applicant is advantageous in that it is unnecessary to increase the number of pixels as compared with the black-and-white screen, even when the display device is applied to the color display system.
An object of the present invention is to provide a display device and a method for producing the same to exhibit the following effects, by improving the arrangement of the illustrative display device suggested by the present applicant.
(1) The clearance (gap) can be easily formed between the optical waveguide plate and the pixel structure, and the gap can be formed uniformly for all of the pixels.
(2) The size of the gap can be easily controlled.
(3) The adhesion of the pixel structure to the optical waveguide plate can be avoided, and it is possible to effectively realize a high response speed.
(4) The contact surface of the pixel structure (contact surface with respect to the optical waveguide plate) can be formed to be smooth so that the light is efficiently introduced into the pixel structure when the predetermined pixel structure makes contact with the optical waveguide plate.
(5) It is possible to ensure the response speed of the pixel.
(6) It is possible to obtain the uniform brightness for all of the pixels.
(7) It is possible to improve the brightness of the pixel.
According to the present invention, there is provided a display device comprising an optical waveguide plate for introducing light thereinto; an actuator substrate provided opposingly to one plate surface of the optical waveguide plate and arranged with actuator elements of a number corresponding to a large number of pixels; a pixel structure formed on each of the actuator elements of the actuator substrate; and a crosspiece formed at a portion other than the pixel structure between the optical waveguide plate and the actuator substrate (invention as defined in claim 1).
According to the present invention, all of the light, which is introduced, for example, from a lateral end of the optical waveguide plate, is totally reflected at the inside of the optical waveguide plate without being transmitted through front and back surfaces thereof by controlling the magnitude of the refractive index of the optical waveguide plate. In this state, when the displacement-transmitting section approaches the optical waveguide plate in accordance with the displacement action of the actuator section, the light, which has been subjected to total reflection, is reflected by the pixel structure, and it behaves as scattered light. A part of the scattered light is reflected again in the optical waveguide plate. However, almost all of the scattered light is transmitted through the front surface of the optical waveguide plate without being reflected by the optical waveguide plate.
The arrangement described above is illustrative of the case in which the pixel structure is displaced in the direction to make approach to the optical waveguide plate in accordance with the displacement action of the actuator element. Alternatively, the present invention is also applicable to the case in which the pixel structure is displaced in the direction to make separation from the optical waveguide plate in accordance with the displacement action of the actuator element.
As described above, the presence or absence of light emission (leakage light) at the front surface of the optical waveguide plate can be controlled in accordance with the approach and separation of the pixel structure disposed at the back of the optical waveguide plate, with respect to the optical waveguide plate. In this arrangement, for example, one unit for allowing the pixel structure to make displacement action in the direction to make the approach or separation with respect to the optical waveguide plate may be regarded as one pixel. A picture image (for example, characters and graphics) corresponding to the image signal can be displayed on the front surface of the optical waveguide plate in the same manner as in the cathode ray tube and the liquid crystal display device, by arranging a large number of the pixels in a matrix form, and controlling the displacement action of each of the pixels in accordance with the attribute of the inputted image signal.
When the display device of the present invention is applied to the color display system, the following arrangement may be adopted, for example, in relation to the color scheme of the color layers (for example, three primary color filters, complementary color filters, or color scattering elements) disposed for the pixel structures. That is, for example, one pixel may be constructed by three pixel structures adjacent to one another (RGB arrangement) or by four pixel structures adjacent to one another (for example, checked arrangement).
It is noted that the display device according to the present invention comprises the crosspiece formed at the portions other than the pixel structures between the optical waveguide plate and the actuator substrate.
If the optical waveguide plate and the actuator substrate are fixed by using only the circumferential edge of the screen without providing any crosspiece, the vibration occurs in the actuator substrate due to the movement of the actuator element. Every time when the vibration occurs, the displacement standard is changed. As a result, the ON/OFF operation of the pixel does not correspond to the displacement of the actuator element in some cases.
However, in the present invention, the crosspiece is provided as described above. Therefore, even when a certain actuator element makes displacement action, the vibration thereof is absorbed by the crosspiece. Accordingly, no inconvenience occurs, which would otherwise occur such that the displacement standard is changed.
The support effected for the optical waveguide plate by the plurality of crosspieces formed around the pixel structure makes it easy to obtain a uniform gap between the pixel structure and the optical waveguide plate for all of the pixels. Further, the size of the gap can be easily controlled by arbitrarily changing the height of the crosspiece. As a result, it is possible to obtain a uniform brightness for all of the pixels.
In the arrangement described above, it is also preferable that the actuator element includes a shape-retaining layer, an operating section having at least a pair of electrodes formed on the shape-retaining layer a vibrating section for supporting the operating section and a fixed section for supporting the vibrating section in a vibrating manner (invention as defined in claim 2).
In the display device constructed as described above, the term xe2x80x9cactuator section including the shape-retaining layerxe2x80x9d refers to an actuator element which has at least two or more displacement states at an identical voltage level.
The actuator element having the shape-retaining layer has the following features.
(1) The threshold characteristic concerning the change from the OFF state to the ON state is steep as compared with the case in which no shape-retaining layer exists. Accordingly, it is possible to narrow the deflection width of the voltage, and it is possible to mitigate the load on the circuit.
(2) The difference between the ON state and the OFF state is distinct, resulting in improvement in contrast.
(3) The dispersion of threshold value is decreased, and an enough margin is provided for the voltage setting range. It is desirable to use, as the actuator element, an actuator element which makes, for example, upward displacement (giving the separated state upon no voltage load and giving the contact state upon voltage application) because of easiness of control. Especially, it is desirable to use an actuator element having a structure including a pair of electrodes on its surface.
(4) It is preferable to use, for example, a piezoelectric/electrostrictive layer and an anti-ferroelectric layer as the shape-retaining layer.
In the display device constructed as described above, it is also preferable that the crosspiece is secured to the optical waveguide plate (invention as defined in claim 3).
Alternatively, it is also preferable that a gap-forming layer is provided between the optical waveguide plate and the crosspiece (invention as defined in claim 4). When the gap-forming layer is provided, it is easier to obtain a uniform gap between the pixel structure and the optical waveguide plate for all of the pixels. The size of the gap can be easily controlled as well.
The constitutive material for the gap-forming layer includes, for example, metal films, films containing carbon black, black pigment, or black dye, and transparent films having low light-scattering property. Accordingly, the gap-forming layer is allowed to simultaneously have the function of black matrix. Especially, when a metal film composed of, for example, Cr, Al, Ni, or Ag is used as the gap-forming layer, the attenuation and the scattering of the light transmitted through the optical waveguide plate can be suppressed, because a small amount of light is absorbed thereby. Therefore, such a metal film is used especially preferably.
When a film containing carbon black, black pigment, or black dye is used as the gap-forming layer, then the light-absorbing performance is excellent, and it is possible to improve the contrast. When a transparent film having a poor light-scattering property is used as the gap-forming layer, then the light scattering can be suppressed, and the contrast can be enhanced by combining the film with an adhesive having an excellent light-absorbing property (or an adhesive having a light-absorbing property enhanced by adding black dye or black pigment).
The size of the gap-forming layer is set as follows, for example, as exemplified by the case in which the actuator element is displaced to be convex toward the optical waveguide plate. That is, the small limit (minimum value) of the gap amount is set to be such a degree that the leakage of light caused by the evanescent effect upon the OFF state of the pixel can be neglected. The large limit (maximum value) of the gap amount is set to be within a range in which the pixel structure can make contact with the optical waveguide plate in accordance with the displacement of the actuator element. Therefore, the thickness of the gap-forming layer is adjusted so that the gap amount is set to be within the range described above. However, the difference in height between the pixel structure and the crosspiece is controllable depending on various embodiments of the display device. The thickness of the gap-forming layer may be optimized in accordance therewith.
In the display device constructed as described above, it is also preferable that the crosspiece is formed at portions around four corners of each of the pixel structure (invention as defined in claim 5). The term xe2x80x9cportions around the four corners of the pixel structurexe2x80x9d includes, for example, positions corresponding to the respective corners when the pixel structure has, for example, a rectangular or elliptic planar configuration. The term refers to a form in which one crosspiece is sheared by the adjoining pixel structure. In this arrangement, four crosspieces are formed for one unit of the pixel structure. Accordingly, the vibration, which is caused by the displacement action of a certain actuator element, is effectively absorbed. As a result, the displacement action of the other actuator elements is scarcely and hardly affected thereby. As a result, the correspondence is well improved between the displacement and the ON operation/OFF operation for all of the pixels. It is possible to faithfully display a picture image corresponding to the inputted image signal. Further, the actuator substrate and the optical waveguide plate are tightly secured to one another.
It is also preferable that the crosspiece is formed to have a window for surrounding at least one pixel structure (invention as defined in claim 6). A representative example is constructed, for example, such that the crosspiece itself is formed to have a plate-shaped configuration, and the window (opening) is formed at a position corresponding to the pixel structure. Accordingly, an arrangement is achieved, in which all side surfaces of the pixel structure are surrounded by the crosspiece. The actuator substrate and the optical waveguide plate are secured to one another more tightly. Further, the vibration caused by the displacement action of a certain actuator element does not affect the displacement action of the other actuator elements at all.
It is also preferable that the crosspiece is constructed such that it includes a stripe-shaped opening which extends along a direction of an array of the pixel structures and which surrounds the array of the pixel structures (invention as defined in claim 7). Alternatively, it is also preferable that the crosspiece is formed to have a line-shaped configuration which extends along a direction of an array of the pixel structures (invention as defined in claim 8).
It is also preferable that the crosspiece is formed integrally with the actuator substrate (invention as defined in claim 9). In this arrangement, it is possible to improve the mechanical strength of the portion at which the crosspiece is formed. Accordingly, the rigidity of the actuator substrate is increased. As a result, the actuator element, which is formed on the actuator substrate, can be protected with the crosspiece, for example, when the actuator substrate is carried or stored. The step of hardening the crosspiece can be omitted, as compared with the case in which the crosspiece is formed separately. Thus, it is possible to reduce the number of production steps.
It is also preferable that the crosspiece is constructed by a wire member which extends along a direction of an array of the pixel structures (invention as defined in claim 10).
In the display device constructed as described above, it is also preferable that a recess is formed on a surface of the pixel structure (invention as defined in claim 11).
In this arrangement, the number of recesses to be formed or the size of the recess is defined depending on the area of the pixel structure opposing to the optical waveguide plate. By doing so, it is possible to provide a substantially identical contact area with respect to the optical waveguide plate concerning the respective pixel structures. Thus, it is possible to obtain a uniform brightness for all of the pixels. The presence of the recess mitigate the tight contact between the pixel structure and the optical waveguide plate. Thus, the pixel structure is smoothly separated from the optical waveguide plate. As a result, the pixel-structure can be prevented from adhesion to the optical waveguide plate. Thus, it is possible to effectively realize a high response speed.
In the display device constructed as described above, it is also preferable that a step is formed on a surface of the pixel structure (invention as defined in claim 12). In this arrangement, the provision of the step on the pixel structure makes it possible to obtain a constant area of the portion of the pixel structure to make contact with the optical waveguide plate for all of the pixels. It is possible to obtain a uniform brightness for all of the pixels. The presence of the step mitigate the tight contact between the pixel structure and the optical waveguide plate. Accordingly, the pixel structure can be prevented from adhesion to the optical waveguide plate, and thus it is possible to effectively realize a high response speed.
In the display device constructed as described above, it is also, preferable that a surface of the pixel structure has a concave configuration (invention as defined in claim 13). When the actuator element makes displacement, the central portion of the pixel structure tends to have the largest displacement amount. Therefore, when the surface of the pixel structure is allowed to have the concave configuration so that the central portion of the pixel structure is concave, the surface of the pixel structure is approximately flat when the actuator element makes displacement to allow the pixel structure to make contact with the optical waveguide plate. Accordingly, it is possible to increase the contact area of the pixel structure with respect to the optical waveguide plate.
When the depth of the concave curve is increased, a state is given, in which the central portion of the pixel structure does not arrive at the optical waveguide plate when the pixel structure makes contact with the optical waveguide plate, giving a state in which a recess is formed on the surface of the pixel structure in a simulated manner. Accordingly, the tight contact between the pixel structure and the optical waveguide plate is mitigated. Thus, the pixel structure is smoothly separated from the optical waveguide plate. As a result, the pixel structure can be prevented from adhesion to the optical waveguide plate, and it is possible to effectively realize a high response speed.
The arrangement in which the recess is formed on the surface of the pixel structure, the arrangement in which the step is formed on the surface of the pixel structure, and the arrangement in which the surface of the pixel structure has the concave configuration may be realized singly respectively, or they may be arbitrarily combined with each other. The combination of them makes it possible to obtain the synergistic effect on the basis of the respective arrangements.
According to another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than actuator elements, of an actuator substrate arranged with the actuator elements corresponding to a large number of pixels; a pixel-forming step of forming pixel structures on the respective actuator elements on the actuator substrate; and a pressurizing step of laminating and pressurizing an optical waveguide plate in a state in which at least the pixel structures are not hardened, and then hardening at least the pixel structures (invention as defined in claim 14).
It is noted that the state in which the pixel structures are not hardened includes a state in which all of stacked films are not hardened, and a state in which a part of films are not hardened, when the pixel structure is constructed by a plurality of stacked films (multiple layered structure).
In this aspect, it is possible to obtain the precise positional alignment for the pixel structure and the crosspiece with respect to the actuator substrate, as well as it is possible to obtain the strong adhesive force. Further, the cleanness of the optical waveguide plate can be highly maintained, because the optical waveguide plate is finally laminated.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than portions corresponding to a large number of actuator elements, of an optical waveguide plate; a pixel-forming step of forming pixel structures at portions corresponding to the large number of pixels, of the optical waveguide plate; and a pressurizing step of laminating an actuator substrate arranged with actuator elements of a number corresponding to the large number of pixels, on the crosspieces and the pixel structures, and pressurizing the optical waveguide plate and the actuator substrate in directions to make approach to one another (invention as defined in claim 15).
In this method, the pixel structures and the crosspieces are formed on the optical waveguide plate, and the actuator substrate is laminated thereon. This method is advantageous in that the area of the pixel (contact area with respect to the optical waveguide plate) is easily defined, because the pixel structures are directly formed on the optical waveguide plate. Further, it is easy, to obtain a uniform brightness for all of the pixels.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than actuator elements, of an actuator substrate arranged with the actuator elements corresponding to a large number of pixels; a pixel-forming step of forming pixel structures at portions corresponding to the large number of pixels, of an optical waveguide plate; and a pressurizing step of laminating a surface of the actuator substrate formed with the crosspieces and a surface of the optical waveguide plate formed with the pixel structures with each other, and pressuring the optical waveguide plate and the actuator substrate in directions to make approach to one another (invention as defined in claim 16).
In this method, the pixel structures are formed on the optical waveguide plate, and the crosspieces are formed on the actuator substrate. After that, the optical waveguide plate and the actuator substrate are laminated with each other.
In this aspect, the formation of the pixel structures and the formation of the crosspieces can be performed in the steps which are independent from each other. Accordingly, the range of material selection is widened concerning the pixel structure and the crosspiece. Thus, it is possible to reduce the production cost and the number of production steps. Further, the size of the pixel structure can be made uniform, because the pixel structures are formed on the optical waveguide plate which has high flatness.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than portions corresponding to a large number of actuator elements, of an optical waveguide plate; a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to the large number of pixels; and a pressurizing step of laminating a surface of the actuator substrate formed with the pixel structures and a surface of the optical waveguide plate formed with the crosspieces with each other, and pressuring the optical waveguide plate and the actuator substrate in directions to make approach to one another (invention as defined in claim 17).
In this method, the crosspieces are formed on the optical waveguide plate, and the pixel structures are formed on the actuator substrate. After that, the optical waveguide plate and the actuator substrate are laminated with each other.
Also in this aspect, the formation of the pixel structures and the formation of the crosspieces can be performed in the steps which are independent from each other. Accordingly, the range of material selection is widened concerning the pixel structure and the crosspiece. Thus, it is possible to reduce the production cost and the number of production steps. Further, the height of the crosspiece can be made strictly uniform, because the crosspieces are formed on the optical waveguide plate which has high flatness. Furthermore, for example, no obstacle (for example, the crosspiece) exists upon the formation of the pixel structure. Therefore, it is possible to accurately, form the pixel structure.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels and integrally having a plurality of crosspieces at portions other than the actuator elements; and a pressurizing step of laminating and pressurizing an optical waveguide plate in a state in which at least the pixel structures are not hardened, and then hardening at least the pixel structures (invention as defined in claim 18).
In this method, the pixel structures are formed on the actuator substrate which is previously provided with the crosspieces in the integrated manner. After that, the optical waveguide plate is laminated and pressurized.
In this aspect, the actuator substrate, which previously has the crosspieces in the integrated manner, it used as the actuator substrate. Therefore, the portion of the crosspiece has high mechanical strength. Accordingly, the rigidity of the actuator substrate is increased. As a result, for example, when the actuator substrate is carried or stored, the crosspieces can be used to protect the actuator elements formed on the actuator substrate. The step of hardening the crosspieces can be omitted, as compared with the case in which the crosspieces are separately formed. Thus, it is possible to reduce the number of production steps.
In the production methods described above, the optical waveguide plate is laminated and pressurized in the state in which at least the pixel structures are not hardened. Accordingly, the optical waveguide plate presses the crosspieces and the pixel structures toward the actuator substrate during the pressurizing process. Thus, a substantially identical surface is formed by the upper surface of the pixel structure and the upper surface of the crosspiece when at least the pixel structure is hardened.
In this aspect, a material, with which the pixel structure is contracted upon the hardening of the pixel structure, is used as the constitutive material for the pixel structure. By doing so, it is possible to form a gap between the optical waveguide plate and the pixel structure during the hardening process for the crosspiece and the pixel structure.
Other methods are available to form the gap. That is, for example, when the optical waveguide plate is laminated and pressurized, the pixel structure is heated and expanded, or the actuator element is displaced to allow the pixel structure to make contact with the optical waveguide plate. It is also possible to adopt a combination of the methods as described above. After that, when the crosspiece and the pixel structure are hardened, a constant gap is formed between the pixel structure and the optical waveguide plate in accordance with the contraction of the pixel structure or the displacement reset (restoration) of the actuator element.
Another arrangement is available, in which the pixel structure contacts with the optical waveguide plate in the natural state. This arrangement is applicable to a case in which the displacement action of the actuator element resides in the displacement of the pixel structure in a direction to make separation from the optical waveguide plate.
In the production methods described above, it is preferable that the crosspiece is hardened, or the crosspiece is partially hardened when the optical waveguide plate is laminated. In this arrangement, the crosspiece acts as a spacer to define the distance between the actuator substrate and the optical waveguide plate.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than actuator elements, of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a pixel-forming step of forming pixel structures on the respective actuator elements of the actuator substrate; a first laminating step of laminating a plate member in a state in which at least the pixel structures are not hardened; a pressurizing step of pressurizing the actuator substrate and the plate member in directions to make approach to one another, and then hardening at least the pixel structures; and a second laminating step of removing the plate member, and then laminating an optical waveguide plate at least on the crosspieces (invention as defined in claim 19).
In this method, the plate member is once laminated on the actuator substrate which is formed with the pixel structures and the crosspieces to give a substantially identical surface for the respective upper surfaces of the pixel structures and the crosspieces. After that, the plate member is removed, and the optical waveguide plate is laminated.
In this aspect, it is possible to obtain the precise positional alignment and the strong adhesive force for the pixel structure and the crosspiece with respect to the actuator substrate.
The crosspieces, which have been formed on the actuator substrate, serve as the spacer when the plate member is laminated and pressurized on the actuator substrate. Thus, the distance is defined between the actuator substrate and the plate member. If the crosspieces are hardened, or if the crosspieces are partially hardened when the optical waveguide plate is laminated, the distance defined as described above corresponds to the distance between the actuator substrate and the optical waveguide plate.
When a smooth plate member is used as the plate member, a smooth surface equivalent to the surface of the plate member is formed on the surface of the pixel structure. The excellent smoothness is useful to improve the brightness when the pixels cause light emission. It is preferable that a releasing agent is applied to the plate member.
In the method described above, it is also preferable that only the crosspieces are subjected to figuring (crosspiece formationxe2x86x92figuring hardening) after the formation of the crosspieces on the actuator substrate. When the plate member is laminated, it is possible to compensate the portion at which the crosspiece does not abut against the plate member, and it is possible to define the height of the crosspiece while absorbing the waviness of the actuator substrate. Further, when the pixel structure is formed, the pixel structure is simultaneously formed on the crosspiece as well to perform the figuring. Also in this arrangement, it is possible to define the height of the crosspiece while absorbing the waviness of the actuator substrate.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising crosspiece-forming step of forming a plurality of crosspieces at portions other than portions corresponding to a large number of pixels, of a plate member; a pixel-forming step of forming pixel structures at the portions corresponding to the large number of pixels, of the plate member; a first laminating step of laminating an actuator substrate arranged with actuator elements of a number corresponding to the large number of pixels on the crosspieces and the pixel structures; a pressurizing step of pressurizing the plate member and the actuator substrate in directions to make approach, to one another; and a second laminating step of removing the plate member to transfer the crosspieces and the pixel structures to the actuator substrate, and then laminating an optical waveguide plate on at least the crosspieces (invention as defined in claim 20).
In this method, the pixel structures and the crosspieces are formed on the plate member. After hardening them respectively, or without hardening them, the actuator substrate is laminated. Subsequently, the plate member is removed, and the optical waveguide plate is laminated.
In this aspect, for example, it is preferable that a releasing agent is applied to the plate member before the crosspieces and the pixel structures are formed on the plate member. By doing so, it is possible to smoothly transfer the pixel structures and the crosspieces to the actuator substrate.
In the present invention, when the actuator substrate is laminated and pressurized on the plate member formed with the crosspieces and the pixel structures, the crosspieces, which have been formed on the plate member, serve as the spacer to define the distance between the actuator substrate and the plate member. When the crosspieces are hardened or partially hardened upon the formation of the crosspieces on the plate member, the defined distance corresponds to the distance between the actuator substrate and the optical, waveguide plate.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than actuator elements, of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a pixel-forming step of forming pixel structures at portions corresponding to the large number of pixels, of a plate member; a first laminating step of laminating a surface of the actuator substrate formed with the crosspieces and a surface of the plate member formed with the pixel structures with each other; a pressurizing step of pressurizing the plate member and the actuator substrate in directions to make approach to one another; and a second laminating step of removing the plate member to transfer the pixel structures to the actuator substrate, and then laminating an optical waveguide plate on at least the crosspieces (invention as defined in claim 21).
In this method, the crosspieces are formed on the actuator substrate, and the pixel structures are formed on the plate member. The actuator substrate and the plate member are laminated with each other. After that, the plate member is removed, and the optical waveguide plate is laminated.
In this aspect, the formation of the pixel structures and the formation of the crosspieces can be performed in the independent steps respectively. Accordingly, the range of material selection is widened concerning the pixel structure and the crosspiece. Thus, it is possible to reduce the production cost and the number of production steps. Further, the size of the pixel structure can be made uniform, because the pixel structures are formed on the plate member which has high flatness.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a crosspiece-forming step of forming a plurality of crosspieces at portions other than portions corresponding to the large number of pixels, of a plate member; a first laminating step of laminating a surface of the actuator substrate formed with the pixel structures and a surface of the plate member formed with the crosspieces with each other; a pressurizing step of pressurizing the plate member and the actuator substrate in directions to make approach to one another; and a second laminating step of removing the plate member to transfer the crosspieces to the actuator substrate, and then laminating an optical waveguide plate on at least the crosspieces (invention as defined in claim 22).
In this method, the pixel structures are formed on the actuator substrate, and the crosspieces are formed on the plate member. The actuator substrate and the plate member are laminated with each other. After that, the plate member is removed, and the optical waveguide plate is laminated.
Also in this aspect, the formation of the pixel structures and the formation of the crosspieces can be performed in the independent steps respectively. Accordingly, the range of material selection is widened concerning the pixel structure and the crosspiece. Thus, it is possible to reduce the production cost and the number of production steps. Further, the height of the crosspiece can be made strictly uniform, because the crosspieces are formed on the plate member which has high flatness. Furthermore, no obstacle (for example, the crosspiece) exists upon the formation of the pixel structure. Therefore, it is possible to accurately form the pixel structure.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels and integrally having a plurality of crosspieces at portions other than the actuator elements; a first laminating step of laminating a plate member in a state in which at least the pixel structures are not hardened; a pressurizing step of pressurizing the actuator substrate and the plate member in directions to make approach to one another, and then hardening at least the pixel structures; and a second laminating step of removing the plate member, and then laminating an optical waveguide plate on at least the crosspieces (invention as defined in claim 23).
In this method, the pixel structures are formed on the actuator substrate which integrally has the crosspieces. Subsequently, the plate member is laminated on the actuator substrate. After that, the plate member is removed, and the optical waveguide plate is laminated.
In this aspect, the mechanical strength of the portion of the crosspiece is high, because the actuator substrate previously having the crosspieces in the integrated manner is used as the actuator substrate. Accordingly, the rigidity of the actuator substrate is increased. As a result, the actuator element, which is formed on the actuator substrate, can be protected with the crosspiece, for example, when the actuator substrate is carried or stored. The step of hardening the crosspiece can be omitted, as compared with the case in which the crosspiece is separately formed. Thus, it is possible to reduce the number of production steps.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a first laminating step of using a jig including, on one surface of a plate member, a large number of size-defining members formed to have substantially the same height as, that of crosspieces to be formed on the actuator substrate to laminate a surface of the jig formed with the size-defining members and a surface of the actuator substrate formed with the pixel structures with each other; a pressurizing step of pressurizing the jig and the actuator substrate in directions to make approach to one another; a crosspiece-forming step of removing the jig, and then forming the plurality of crosspieces at portions other than the actuator sections, of the actuator substrate; and a second laminating step of laminating an optical waveguide plate on at least the crosspieces on the actuator substrate (invention as defined in claim 24).
In this method, the pixel structures are formed on the actuator substrate. Subsequently, the jig including the large number of size-defining members formed on the plate member and the actuator substrate are laminated and pressurized, and thus the size of the pixel structures is defined. After that, the jig is removed, the crosspieces are formed on the actuator substrate, and then the optical waveguide plate is laminated.
In this aspect, for example, when the jig is constructed by a member having rigidity such as metal, the waviness of the actuator substrate formed with the pixel structures can be reduced by laminating and pressurizing the jig and the actuator substrate. The crosspieces can be formed highly accurately in the crosspiece-forming step performed thereafter.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels: a first laminating step of using a jig including, on one surface of a plate member, a large number of size-defining members formed to have substantially the same height as that of crosspieces to be formed on the actuator substrate to laminate a surface of the jig formed with the size-defining members and a surface of the actuator substrate formed with the pixel structures with each other; a pressurizing step of pressurizing the jig and the actuator substrate in directions to make approach to one another; a crosspiece-forming forming step of removing the jig, and then forming the plurality of crosspieces at portions other than portions corresponding to the large number of pixels, of an optical waveguide plate; and a second laminating step of laminating a surface of the actuator substrate formed with the pixel structures and a surface of the optical waveguide plate formed with the crosspieces with each other (invention as defined in claim 25).
In this method, the pixel structures are formed on the actuator substrate. Subsequently, the jig including the plate member provided with the large number of size-defining members and the actuator substrate are laminated with each other to pressurize them. Thus, the size of the pixel structures is defined. After the jig is removed, the crosspieces are formed on the optical waveguide plate, and the optical waveguide plate and the actuator substrate are laminated with each other.
Also in this aspect, for example, when the jig is constructed by a member having rigidity such as metal, the waviness of the actuator substrate formed with the pixel structures can be reduced by laminating and pressurizing the jig and the actuator substrate. The optical waveguide plate can be laminated highly accurately thereafter. Further, the height of the crosspiece can be made strictly uniform, because the crosspieces are formed on the optical waveguide plate which has high flatness.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a pixel-forming step of forming pixel structures on respective actuator elements of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a crosspiece-forming step of using a jig including, on one surface of a plate member, a large number of size-defining members formed to have substantially the same height as that of crosspieces to be formed on the actuator substrate to form the plurality of crosspieces at portions formed with no size-defining member, of a surface of the jig formed with the size-defining members, the portions being other than portions corresponding to the large number of pixels; a first laminating step of laminating the surface of the jig formed with the size-defining members and the crosspieces and a surface of the actuator substrate formed with the pixel structures with each other; a pressurizing step of pressurizing the jig and the actuator substrate in directions to make approach to one another; and a second laminating step of removing the jig to transfer the crosspieces to the actuator substrate, and then laminating an optical waveguide plate on at least the crosspieces on the actuator substrate (invention as defined in claim 26).
In this method, the pixel structures are formed on the actuator substrate, and the crosspieces are formed on the jig including the plate member provided with the large number of size-defining members. The actuator substrate and the jig are laminated with each other to pressurize them. Thus, the size of the pixel structures is defined. After that, the jig is removed, the crosspieces are transferred to the actuator substrate, and the optical waveguide plate is laminated.
Also in this aspect, for example, when the jig is constructed by a member having rigidity such as metal, the waviness of the actuator substrate formed with the pixel structures can be reduced by laminating and pressurizing the jig and the actuator substrate. The crosspieces and the pixel structures can be formed highly accurately.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than actuator elements, of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a pixel-forming step of forming pixel structures on the respective actuator elements of the actuator substrate; a first laminating step of using a jig including, on one surface of a plate member, a large number of size-defining members formed to have substantially the same height as that of the crosspieces to be formed on the actuator substrate to laminate a surface of the jig formed with the size-defining members and a surface of the actuator substrate formed with the crosspieces and the pixel structures with each other; a pressurizing step of pressurizing the jig and the actuator substrate in directions to make approach to one another; and a second laminating step of removing the jig, and then laminating an optical waveguide plate on at least the crosspieces on the actuator substrate (invention as defined in claim 27).
In this method, the pixel structures and crosspieces are formed on the actuator substrate. The actuator substrate and the jig including the plate member provided with the large number of size-defining members are laminated with each other to pressurize them. Thus, the size of the crosspieces and the pixel structures is defined. After that, the jig is removed, and the optical waveguide plate is laminated.
Also in this aspect, for example, when the jig is constructed by a member having rigidity such as metal, the waviness of the actuator substrate formed with the pixel structures and the crosspieces can be reduced by laminating and pressurizing the jig and the actuator substrate. The crosspieces and the pixel structures can be formed highly accurately.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of forming a plurality of crosspieces at portions other than actuator elements, of an actuator substrate arranged with the actuator elements of a number corresponding to a large number of pixels; a pixel-forming step of using a jig including, on one surface of a plate member, a large number of size-defining members formed to have substantially the same height as that of the crosspieces to be formed on the actuator substrate to form pixel structures at portions corresponding to the large number of pixels, the portions being formed with no size-defining member, of a surface of the jig formed with the size-defining members; a first laminating step of laminating the surface of the jig formed with the size-defining members and the pixel structures and a surface of the actuator substrate formed with the crosspieces with each other; a pressurizing step of pressurizing the jig and the actuator substrate in directions to make approach to one another; and a second laminating step of removing the jig to transfer the pixel structures to the actuator substrate, and then laminating an optical waveguide plate on at least the crosspieces on the actuator substrate (invention as defined in claim 28).
In this method, the crosspieces are formed on the actuator substrate. The pixel structures are formed on the jig including the plate member provided with the large number of size-defining members. The actuator substrate and the jig are laminated with each other to pressurize them. Thus, the size of the crosspieces and the pixel structures is defined. After that, the jig is removed, the pixel structures are transferred to the actuator substrate, and then the optical waveguide plate is laminated.
Also in this aspect, for example, when the jig is constructed by a member having rigidity such as metal, the waviness of the actuator substrate formed with the pixel structures can be reduced by laminating and pressurizing the jig and the actuator substrate. The crosspieces and the pixel structures can be formed highly accurately.
According to still another aspect of the present invention, there is provided a method for producing a display device, comprising a crosspiece-forming step of using a jig including, on one surface of a plate member, a large number of size-defining members formed to have substantially the same height as that of crosspieces to be formed on an actuator substrate to form the plurality of crosspieces at portions formed with no size-defining member, of a surface of the jig formed with the size-defining members, the portions being other than portions corresponding to a large number of pixels; a pixel-forming step of forming pixel structures at portions corresponding to the large number of pixels, the portions being formed with no size-defining member, of the surface of the jig formed with the size-defining members; a first laminating step of laminating the actuator substrate arranged with actuator elements of a number corresponding to the large number of pixels on the crosspieces and the pixel structures on the jig; a pressurizing step of pressurizing the jig and the actuator substrate in directions to make approach to one another; and a second laminating step of removing the jig to transfer the crosspieces and the pixel structures to the actuator substrate, and then laminating an optical waveguide plate on at least the crosspieces (invention as defined in claim 29).
In this method, the crosspieces and the pixel structures are formed on the jig including the plate member formed with the large number of size-defining members. The jig and the actuator substrate are laminated with each other to pressurize them. Thus, the size of the crosspieces and the pixel structures is defined. After that, the jig is removed, the crosspieces and the pixel structures are transferred to the actuator substrate, and the optical waveguide plate is laminated.
Also in this aspect, for example, when the jig is constructed by a member having rigidity such as metal, the waviness of the actuator substrate can be reduced by laminating and pressurizing the jig and the actuator substrate. The crosspieces and the pixel structures can be transferred to the actuator substrate highly accurately.
In the production methods in which the crosspieces are formed on the plate member or the jig, of the production methods described above, it is also preferable that the members for constructing the crosspieces are laminated on the plate member or the jig by utilizing surface tension of liquid (invention as defined in claim 30). In this arrangement, the plate member or the jig can be easily removed thereafter.
In the production methods in which the crosspieces are formed on the plate member or the jig, of the production methods described above, it is also preferable that the crosspieces are formed at the concerning portions of the plate member or the jig, and then the crosspieces are hardened (invention as defined in claim 31).
It is also preferable that in the pressurizing step of the production methods described above, at least the pixel structures are hardened while pressurizing the actuator substrate and the member to be pressurized together with the actuator substrate (invention as defined in claim 32). It is also preferable that the optical waveguide plate includes a gap-forming layer at a portion corresponding to the crosspiece (invention as defined in claim 33).
In the methods described above, it is also preferable that a gap-forming layer is previously formed on the crosspiece before laminating the optical waveguide plate (invention as defined in claim 34). In this arrangement, the presence of the gap-forming layer makes it easier to obtain a uniform gap between the pixel structure and the optical waveguide plate for all of the pixels. The size of the gap can be easily controlled as well.
When the optical waveguide plate, the plate member, or the jig is laminated and pressurized in the state in which at least the pixel structures are not hardened upon the lamination of the plate member or the jig and the actuator substrate or upon the lamination of the optical waveguide plate and the actuator substrate, the optical waveguide plate, the plate member, or the jig presses the crosspieces and the pixel structures toward the actuator substrate during the pressurizing process. The upper surface of the crosspiece and the upper surface of the pixel structure form a substantially identical surface at least when the pixel structures are hardened.
In this arrangement, a material, with which the pixel structure is contracted upon the hardening of the pixel structure, is used as the constitutive material for the pixel structure. By doing so, it is possible to form a gap between the pixel structure and the optical waveguide plate during the hardening of the crosspiece and the pixel structure.
Other methods are available to form the gap. That is, for example, when the optical waveguide plate is laminated and pressurized, the pixel structure is heated and expanded, or the actuator element is displaced to allow the pixel structure to make contact with the optical waveguide plate. It is also possible to adopt a combination of the methods as described above. After that, when the crosspiece and the pixel structure are hardened, a constant gap is formed between the pixel structure and the optical waveguide plate in accordance with the contraction of the pixel structure or the displacement reset (restoration) of the actuator element.
Another arrangement is available, in which the pixel structure contacts with the optical waveguide plate in the natural state. This arrangement is applicable to a case in which the displacement action of the actuator element resides in displacement in a direction in which the pixel structure is separated from the optical waveguide plate.
In the production methods described above, it is preferable that the crosspiece is hardened, or the crosspiece is partially hardened when the plate member or the optical waveguide plate is laminated on the actuator substrate. In this arrangement, the crosspiece acts as a spacer to define the distance between the actuator substrate and the plate member or the optical waveguide plate.
It is also preferable that when the actuator substrate and the member (the optical waveguide plate, the plate member, or the jig) to be pressurized together with, the actuator substrate are pressurized, a preliminary treatment is performed for gap formation, and a predetermined gap is formed between the pixel structure and the optical waveguide plate during the hardening of at least the pixel structures performed thereafter (invention as defined in claim 35).
This arrangement resides in the method having been already explained. That is, when the optical waveguide plate, the plate member, or the jig is laminated and pressurized, the pixel structure is heated and expanded, or the actuator element s, displaced to allow the pixel structure to make contact with the optical waveguide plate, the plate member, or the jig. When this method is adopted, it is easy to form a constant gap between the pixel structures and the optical waveguide plate. It is possible to obtain a uniform brightness for all of the pixels.
Especially, it is preferable that a vacuum packaging method is used to pressurize the actuator substrate and the member (the optical waveguide plate, the plate member, or the jig) to be pressurized together with the actuator substrate (invention as defined in claim 36). That is, for example, even when the actuator substrate involves warpage and waviness, it is possible to uniformly pressurize the actuator substrate and the optical waveguide plate, the plate member, or the jig. Accordingly, the optical waveguide plate, the plate member, or the jig and the actuator substrate are adopted to one another. Therefore, when the optical waveguide plate is laminated, a constant gap can be finally formed between all of the pixel structures and the optical waveguide plate.
If the thickness is dispersed among the pixel structures, the displacement (displacement amount) of the actuator element after the formation of the pixel is greatly dispersed. However, according to this method, the thickness is uniformly formed for all of the pixel structures. Therefore, it is possible to suppress such dispersion in displacement (displacement amount) of the actuator element.
Owing to the fact that the dispersion scarcely occurs in the thickness of the pixel structure, there is no dispersion in deformation of the pixel structure caused by thermal expansion or contraction. It is advantageous that the dispersion hardly appears in gap amount even when any heat is exerted.
It is also preferable that a low pressure press method is used to pressurize the actuator substrate and the member (the optical waveguide plate, the plate member, or the jig) to be pressurized together with the actuator substrate (invention as defined in claim 37). In this arrangement, it is possible to decrease the stress applied to the actuator substrate. Therefore, it is possible to avoid any damage or the like of the actuator element. Further, little deformation occurs in the actuator substrate and the optical waveguide plate due to the lamination, and the residual stress is small. Accordingly, it is possible to improve the stability and the durability of the gap.
In the methods described above, it is also preferable that the member (the plate member or the jig), which is used to be laminated on the actuator substrate in the first laminating step, has a projection at a portion corresponding to each of the pixel structures, and a recess corresponding to the projection is formed on the surface of the pixel structure when the plate member or the jig and the actuator substrate are pressurized (invention as defined in claim 38).
In the methods described above, it is also preferable that the member (the plate member or the jig), which is used to be laminated on the actuator substrate in the first laminating step, has a projection at a portion corresponding to each of the pixel structures, and a step corresponding to the projection is formed on the surface of the pixel structure when the plate member or the jig and the actuator substrate are pressurized (invention as defined in claim 39).
In the methods described above, it is also preferable that the member (the plate member or the jig), which is used to be laminated on the actuator substrate in the first laminating step, has a convex configuration formed at a portion corresponding to each of the pixel structures.,and a concave configuration corresponding to the convex configuration is formed on the surface of the pixel structure when the plate member or the jig and the actuator substrate are pressurized (invention as defined in claim 40).
The crosspiece and the pixel structure may be formed by using the film formation method and the ceramic sintering method. The film formation method includes the thick film formation method such as the screen printing, the photolithography method, the film lamination method, the spray dipping, the application, and the stamping (the method for placing a liquid material as if a stamp is put); and the thin film formation method such as the ion beam, the sputtering, the vacuum evaporation, the ion plating, CVD, and the plating.
The plate member having the projection on the surface is used in the method for forming the recess and the step on the surface of the pixel structure. For this purpose, it is preferable to use a method in which a metal film or a resist film is formed by the general thin film formation method on a plate member composed of glass. This method is advantageous in that the pattern and the height of the projection can be arbitrarily changed. It is preferable that the height of the projection is about 0.1 to 2 xcexcm.
Other methods are available to form the recess or the step on the surface of the pixel structure. It is possible to use the plane polishing and the laser beam-based surface processing for the surface of the pixel structure. The laser processing is not directed to the formation of the recess, but it also has an effect of surface improvement by means of heating. Further, it is possible to arbitrarily design the processing pattern. Therefore, the laser processing is used especially preferably.
The method for forming the concave configuration of the surface of the pixel structure includes a method of heating and a method in which a voltage is applied to the actuator element during the hardening of the pixel structure. There are a method in which heating is effected during the figuring hardening with the plate member, and a method in which heating is effected after removing the plate member. It is possible to select the method depending on the material quality of the pixel structure. The usable heating temperature is 15xc2x0 C. to 150xc2x0 C. Especially, a temperature of 20xc2x0 C. to 80xc2x0 C. is preferably used.